Tumors of Schwann’s Cells and Pigmented Skin Cells

Embryonic Chicken Transplantation is a Promising Model for Studying the Invasive Behavior of Melanoma Cells

Epithelial-to-mesenchymal transition is a hallmark event in the metastatic cascade conferring invasive ability to tumor cells. There are ongoing efforts to replicate the physiological events occurring during mobilization of tumor cells in model systems. However, few systems are able to capture these complex in vivo events. The embryonic chicken transplantation model has emerged as a useful system to assess melanoma cells including functions that are relevant to the metastatic process, namely invasion and plasticity. The chicken embryo represents an accessible and economical 3-dimensional in vivo model for investigating melanoma cell invasion as it exploits the ancestral relationship between melanoma and its precursor neural crest cells. We describe a methodology that enables the interrogation of melanoma cell motility within the developing avian embryo. This model involves the injection of melanoma cells into the neural tube of chicken embryos. Melanoma cells are labeled using fluorescent tracker dye, Vybrant DiO, then cultured as hanging drops for 24 h to aggregate the cells. Groups of approximately 700 cells are placed into the neural tube of chicken embryos prior to the onset of neural crest migration at the hindbrain level (embryonic day 1.5) or trunk level (embryonic day 2.5). Chick embryos are reincubated and analyzed after 48 h for the location of melanoma cells using fluorescent microscopy on whole mounts and cross-sections of the embryos. Using this system, we compared the in vivo invasive behavior of epithelial-like and mesenchymal-like melanoma cells. We report that the developing embryonic microenvironment confers motile abilities to both types of melanoma cells. Hence, the embryonic chicken transplantation model has the potential to become a valuable tool for in vivo melanoma invasion studies. Importantly, it may provide novel insights into and reveal previously unknown mediators of the metastatic steps of invasion and dissemination in melanoma.

Oncocytoma in melanocytoma of the spinal cord: case report

OBJECTIVE AND IMPORTANCE

Oncocytoma in the central nervous system is extremely unusual. The first reported example of oncocytoma in a melanocytoma of the spinal cord was successfully excised, and its pathological appearance is described.

CLINICAL PRESENTATION

A 71-year-old woman presented with a 25-year history of back pain and myelographic evidence of a lumbar spinal cord mass. After declining surgical treatment for two decades, she elected eventually to have the mass excised. Preoperative magnetic resonance imaging revealed a large intraspinal mass that spanned spinal levels L3 through S1.

TECHNIQUE

The mass was excised en bloc through posterior laminectomies, and histopathological analysis revealed a benign neoplasm composed predominantly of monotonous sheets of plump oncocytes. Electron microscopy confirmed that the cytoplasm of the oncocytes was packed full of mitochondria. Focal areas of the tumor contained spindle cells, with abundant intracytoplasmic granular deposits of brown melanin pigment that contained melanosomes. Positive Fontana-Masson, HMB-45, and S-100 staining confirmed the final diagnosis of melanocytoma, oncocytic variant.

CONCLUSION

The first reported case of oncocytoma arising in spinal melanocytoma is described. After surgical excision, the patient recovered completely and has remained free of symptoms for 4 years.

Electron microscopy of large cell undifferentiated and giant cell tumors

Electron microscopy is a valuable morphologic method for the diagnostic evaluation of undifferentiated tumors composed of polygonal or oval large cells and mononuclear or multinucleated giant cells. Although few ultrastructural details are pathognomonic, electron microscopic findings may add significantly to the formulation of the final diagnosis if used in the context of other pathomorphologic and clinical data. Contributions of electron microscopy to tumor diagnosis are summarized and illustrated with appropriate examples from personal experience in a routine university hospital laboratory.